The New York Times reports on the FDA's approval of a stem cell therapy in humans. Andrew Pollack writes,

In a research milestone, the federal government will allow the world’s first test in people of a therapy derived from human embryonic stem cells. Federal drug regulators said that political considerations had no role in the decision. Nevertheless, the move coincided with the inauguration of President Obama, who has pledged to remove some of the financing restrictions placed on the field by President George W. Bush. The clearance of the clinical trial — of a treatment for spinal cord injury — is to be announced Friday by Geron, the biotechnology company that first applied to the Food and Drug Administration to conduct the trial last March. The F.D.A. had first said no, asking for more data.

Thomas B. Okarma, Geron’s chief executive, said Thursday that he did not think that the Bush administration’s objections to embryonic stem cell research played a role in the F.D.A.’s delaying approval. “We really have no evidence,” Dr. Okarma said, “that there was any political overhang.” But others said they suspected it was more than a coincidence that approval was granted right after the new administration took office. “I think this approval is directly tied to the change in administration,” said Robert N. Klein, the chairman of California’s $3 billion stem cell research program. He said he thought the Bush administration had pressured the F.D.A. to delay the trial. . . .

The F.D.A. approval comes a little more than 10 years after the first human embryonic stem cells were isolated at the University of Wisconsin, in work financed by Geron. Because the cells can turn into any type of cell in the body, the theory is they may one day be able to provide tissues to replace worn-out organs or nonfunctioning cells to treat diabetes, heart attacks and other diseases. The field is known as regenerative medicine. . . .

Geron’s trial will involve 8 to 10 people with severe spinal cord injuries. The cells will be injected into the spinal cord at the injury site 7 to 14 days after the injury occurs, because there is evidence the therapy will not work for much older injuries. The study is a so-called Phase I trial, aimed mainly at testing the safety of the therapy. There would still be years of testing and many hurdles to overcome before the treatment would become routinely available to patients. . . .

Even as some researchers hailed the onset of clinical trials, others expressed trepidation that if the therapy proves unsafe — or even if it is safe but does not work — it could cause a backlash that would set the field back for years. “It would be a disaster, a nightmare, if we ran into these kinds of problems in this very first trial,” said Dr. John A. Kessler, the chairman of neurology and director of the stem cell institute at Northwestern University. Dr. Kessler, whose own daughter was paralyzed from the waist down in a skiing accident, said he thought Geron’s therapy was not the ideal candidate for the first trial. He said results showing the therapy worked in moderately injured animals might not apply to more seriously injured people. “We really want the best trial to be done for this first trial, and this might not be it,” he said. . . .

The main safety concern is that if raw embryonic cells are put into the body, they can form tumors. Even though most such tumors do not spread like other cancers, any unwanted growth in the spinal cord can further damage nerves. . . .